On 19-21 September, the 16th Clean Up the World weekend will see millions of volunteers come together in more than 100 countries to clean up their environment.

The theme of this year's event is 'Start Today... Save Tomorrow - Clean Up our Climate'.

One focus is the tide of trash polluting the world's seas-it is estimated there are more than 13,000 pieces of plastic in every square kilometre of ocean.

Australian Ian Kiernan launched Clean Up the World 16 years ago with the support of the United Nations Environment Programme (UNEP) after he was shocked by the large amounts of rubbish he saw during a solo round-the-world ocean race.

The event now mobilizes an estimated 35 million volunteers from more than 110 countries every year, making it one of the largest community-based environmental campaigns in the world.

During the weekend local communities will take action on a number of environmental issues, including protecting water sources, saving energy and reducing waste.